The present invention relates to light bars for emergency vehicles, such as police cars, ambulances and fire trucks. Presently known light bars employ various combinations of fixed lights, rotating lights or rotating reflectors, to produce flashing light images to attract the attention of motorists on the highway. They also include one or more sirens to warn the motorist of the approaching emergency vehicle.
These electromechanical devices involve drive motors, slip rings, gears, bearings and ladder chains; all of which have limited life and present some severe field reliability problems, particularly in very high or low temperatures. In addition the motor brushes and slip rings produce arcing in normal operation that must be filtered out of any radio signals.
The single function of the light bar is to communicate some form of command to the motorist. This is of critical importance in terms of both public safety and officer safety. Present light bars simply display a jumble of flashing lights of very short flash duration. The motorist often does not even see an emergency vehicle immediately behind him, and it is commonplace for a police car to follow a motorist for miles with the light bar and siren on, only to have the motorist say he did not notice the police car at all. In a well sound-proofed car, with curved and tinted windows rolled up and a stereo playing, it is often a true statement.
If and when a motorist does see the lights of an emergency vehicle behind him he has no idea of what he is supposed to do. If he is driving in one of the center lanes of a freeway, he doesn't know whether to pull over to the left or right shoulder, or stop right there.
If the motorist sees a light bar operating ahead, he also doesn't know whether to stop, pass on the right, or pass on the left. A much feared occurance is when the decision is made too late, and the motorist simply plows into the emergency vehicle or other vehicles in an accident.
Prior art light bar controls are fairly complex, and have little logical correlation between the manipulation of the controls, the operation desired of the light bar system, or the operational functions being performed. It takes an experienced operator that is familiar with the controls of a specific system to work the controls without looking at them. This can be very hazardous in terms of both public safety and operator safety. The operator often has to initiate or change light bar operation under extreme duress of conditions involving high speed driving, radio reception and transmission, keeping track of and reporting location and direction, driving in adverse weather, and watching both suspects and bystanders. Glancing down at the light bar control for a fraction of a second can be hazardous or fatal to the operator and others.
Prior art light bar controls also leave many operational decisions up to the individual in the emergency vehicle, and he therefore decides on the spur of the moment what mode of light and siren operation to use in pursuit, moving through freeway or highway traffic, crossing intersections, pulling over a suspect, over taking a vehicle, controlling traffic, stopping a vehicle, etc. This practically eliminates standardization of operational procedures, making training more difficult, and increasing potential liability for the operator's employer.